1. Field of the Invention
The present invention relates to serving signals to browsing clients, wherein said signals represent commands executable by said browsing clients for generating structured pages of human viewable data.
2. Related Art
The serving of human viewable data in response to client requests has been known for some years in the field of cable television systems. Star type systems in particular allow viewers to make selections resulting in remote switching being performed so as to route a selected signal from a distribution head to the requesting viewer. Cable television systems are usually based on standard broadcast television signals and, as a result, a substantial transmission bandwidth is required in order to provide each viewable page of data. Recently, attempts have been made to compress video date, by implementing recommendations using standards such as MPEG, so as to facilitate the distribution of video signals over channels of substantially less bandwidth. Thus, it is now possible to transmit low quality video signals over conventional telephone lines using temporal and spatial compression techniques.
It has also been possible to distribute human viewable data in the form of encoded text for a number of years. The transmission of text, often using ASCII coding, requires substantially less bandwidth than the transmission of video signals and for a number of years data of this type has been transmitted over conventional telephone cables.
A problem with transmitting conventional data text, compared to image related video signals, is that the quality of presentation and overall graphical format is significantly impaired. For this reason, traditionally, the transmission of data, as distinct from video, has tended to develop only in specialist fields where presentation was not considered particularly important. Very often, for example, the data being received would be considered as being quite valuable and very often it would be possible to justify the re-typing of information as and when required.
A further problem with the dissemination of data is that many standards and conventions have developed over the years. Therefore, traditionally, users have needed to develop techniques for accessing different data sources, which in itself has tended to become a specialist activity.
In parallel with the tendency towards bandwidth reduction in the transmission of video signals, there has also been a tendency towards improving the graphical format, structure and presentation of what would normally be considered as textural data. Thus, although data may be transmitted within a text-based environment, such as within the internationally accessible network known as the "Internet", there has been a tendency towards including formatting structures such that a substantially data-driven source could be viewed by a user on equipment which would present the data in a form substantially similar to that of a video image. Thus, the two arts of video signal processing and image data processing are coming closer together and reaching towards a common aim of providing what appears to be a high resolution, high bandwidth, high quality image by transmitting data over low bandwidth transmission media
For a number of years, cable television systems have been used to provide in-home shopping facilities and, given their two-way capabilities, it is possible to install a level of interactivity within such systems. On-line systems facilitate a higher level of interactivity and, in addition to making particular selections in response to images being broadcast, it is also possible to select particular image pages by browsing through catalogues and tree structures etc. Thus, given an ability to display high quality images, similar to those available through video based systems, on-line systems present environments with substantially more interactive capabilities. However, it is appreciated that in many of these environments the quality of images must be significantly enhanced in order to attain a broad customer base.
A known way of improving the quality of images derived from text-based systems is to add formatting commands or instructions to data strings. These instructions control operations of a receiver, such that the signals are processed in such a receiver, to ensure that the transmitted signals are processed in such a way as to generate a high quality video image that is capable of being displayed at a requesting client's terminal.
In addition to improving the quality of displayed images, such an approach also facilitates an improvement in system compatibility. Thus, the incoming control signals are executed by a receiver's terminal in a way that is compatible with the receiving system. Thus, the output signals may be considered as executable instructions that cause operations to be performed upon the viewable data in accordance with the local constraints.
Thus, the use of systems of this type must be distinguished from simple local database systems in which all operations of the system are locally controlled and no account whatsoever needs to be taken of remote facilities and characteristics. Such systems are significantly different in that database systems only transfer data that is subsequently manipulated by controlling programs. In mark-up languages the formatting commands are embedded in the form of executable commands, executable at the receiving station, so as to perform operations upon the viewable data supported by the local platform and peripherals.
Mark-up languages of this type may also include other capabilities previously not found in simple data distribution systems. In particular, a highly valued additional feature is the ability to automatically receive additional files from anywhere within the overall network. Such a procedure is possible because, as previously stated, the mark-up language is effectively executed by the local platform and these executable procedures may include procedures for making external calls to files held anywhere within the accessible network.
From a user's point of view, such links may be considered as providing a level of multi-dimensionality within a viewable document in that a particular word or phrase may be selected, whereafter an expansion is provided or related documents are identified. In order to distinguish such documents from ordinary self-contained documents, text of this type is commonly referred to as "hypertext". Similarly, such links may also be made to full motion video sequences or audio sequences etc. and such an environment may be referred to as "hypermedia".
An example of a particular recommendation under which signals include commands executable by browsing clients is the "hypertext mark-up language" (HTML) developed at CERN during the late 1980s and early 1990s, which has recently become a part of the Internet through a service known as the "World Wide Web". An (HTML) file is essentially an ASCII document interspersed with tags for formatting text and displaying images. The tags graphically represent instructions which are acted upon by a receivers browser, configured to render text or graphics. The browser has full control of how the page is displayed, therefore it is possible to generate a wide range of page lay-outs from a modest set of (HTML) tags.
The Internet is an extreme example of a network in which many different types of platforms, having various protocols and processing capabilities, may be interconnected using highly distributed control instruction sets. As previously suggested, systems of this type often provide an environment in which a user may "browse" through many files and structures. Consequently environments to facilitate the reception and conversion of HTML files are commonly known as "browsers". Thus, a browser is an application capable of interpreting and displaying documents received in HTML in such a way that the information is displayed to the user in a form compatible with the user's available equipment. Thus, using sophisticated terminal equipment, provided with an appropriate browser, it is possible to display text-based data at a quality that is perceived as being substantially similar to that of full bandwidth video, while significantly reducing the level of bandwidth required in order to distribute the information. Thus, as previously stated, the purpose of the browser is to substantially improve the quality of the displayed image such that a client user is presented with a high quality video image, if suitable equipment is available. In addition, the browser ensures that compatibility is achieved between the local system facilities and the transmitted data. Furthermore, hypertext links may be defined within the document that are executed by the browser so as to make additional documents available in response to user driven selections.
Clearly, it is only possible for client users to make use of these sophisticated languages if networks include accessible data sources. HTML files may be stored in file structures that are substantially similar to conventional data formats. Requests are made, via client browsers to applications maintained at a distribution node, commonly referred to as "serers".
Both browsers and servers represent applications which must be made available when requested although, during substantially quiet periods of operation, there are not actually required as such. Procedures of this type, embedded within systems and substantially transparent to operators, have become known, collectively, as "daemnons". Thus, in operation, server daemons intermittently interrogate selected ports for incoming signal requests. In response to these requests, servers may make appropriate housekeeping and security operations, whereafter, if possible, the selected file is identified and supplied to the requesting browser.
In earlier simple ASCII based text systems, the generation of text in a form suitable for transmission over networks involved relatively easy operations. Generally, documents could be accessed from text files or databases and transmitted directly across the network. At the receiver, the input data would often be buffered, but thereafter it could be supplied directly to line printers, or similar devices, thereby producing a listing or print out of the transmitted ASCII text.
As previously stated, HTML allows sophisticated formatting structures to be added to the viewable data so as to present a substantially more appealing image to client users. However, a major disadvantage of using such systems is that it is necessary to convert source data into HTML form before it may be transmitted over the network. In practice, such a procedure is presently performed manually and a significant number of man hours may be required in order to convert originating text into an appropriate HTML version suitable for distribution throughout the network.
In some environments, such as research environments etc., data may be required for significant periods of time and under such circumstances it is possible to justify the time and effort required in order to mark up the text for distribution throughout a network in an appropriate form. However, as is well known in the magazine and newspaper arts, some forms of data, although initially highly valuable, may have very short "shelf lives" and, even the next day, they may become virtually worthless. Thus, many forms of existing paper publications may be withheld from electronic publishing if the amount of time and effort required to covert the text-based information into a form suitable for distribution throughout networks is significantly large. Furthermore, in many situations, the extent to which the time scale for performing an exercise may be reduced by increasing manpower, may be restricted, given that it is only possible for one person to work on one page at any one instant.
Traditional marking-up is a laborious task, given that, by its very nature, the actual transmitted data looks very different from the viewed image. In most situations, it is necessary for a level of marking-up to be performed, whereafter the data is transferred to a locally situated browser, so that the resulting viewable image may be considered, before further operations are performed. Once created, files are loaded on appropriate storage devices and thereafter made available to requesting customers.
Systems are available which facilitate the creation of (HTML) documents. For example, it is possible to process documents generated under word processing systems, such as "Word for Windows", whereby, in response to manual operations, (HTML) tags are added to human viewable text. Systems of this type are sold under the Trade Marks "WebAuthor" and "Internet Assistant".
It is well known that traditional newspapers tend to change slightly over a day, as various editions are modified so as to take account of recent news items. Thus, very often, a late edition of a newspaper will carry a different main story to that of earlier editions. Within electronic environments, there is an expectation for an even higher level of updating and interactivity.
Presently, in order to satisfy this expectation, it would be necessary to continually update pages manually.
Systems have been proposed in which clients are given the impression that a magazine has been tailored to their particular needs. Thus, systems are known in which particular selections may be made thereby tuning documents to customer requirements. A problem with known approaches of this type is that each page viewed by a client must be pre-created, thereby doubling the number of pages required each time a decision point occurs. Such an approach may have applications in particular environments but it can be appreciated that as the number of notional pages increases, the number of actual pages required within the system becomes extremely large and the task of creating and maintaining each of these pages manually would be highly laborious and very often make the system uneconomic. This is particularly the case when dealing with publications which, in their conventional paper form, are perceived as having relatively low value or often no intrinsic value at all. Such a situation would apply to free newspapers and advertising catalogues etc.